Means for regulating electric motors.



No. 7|I,667. Patantod Oct. 2l, |902. R. LUNDELL. MEANS FOR BEGULATINGELECTRIC MOTORS.

Applitonlad Icy 10 1902) (lo Indem @@wlwi 25g@ @wl Snom/vbo@ Witmzom @id6. @Maf UNITED STATES PATENT OFFICE.

ROBERT LUNDELL, OF NEWV YORK, N. Y.

MEANS FOR REGULATING ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 711,667, dated October21, 1902.

Application tiled May 10, 1902. Serial No. 106,728. (No model.)

To @ZZ 1,071,012?, it nw/y concern:

Beit known that I, ROBERT LUNDELL, a citizen of the United States,residing in New York, borough of Manhattan, county and State of NewYork, have made a new and useful Invention in Means for RegulatingElectric Motors, of which the following is a specification.

My present invention relates particularly to the regulation of electricmotors used in connection with storage batteries or similar sources ofelectromotive forces and is speh cially applicable to motors propellingelectric cars or vehicles.

The generic features of the invention are somewhat similar to thosedescribed and claimed in a prior United States patent, No. 626,178,granted to me on the 30th day of May, 189i).

The invention has for its chief objects, iirst, to provide means forcontrolling the speed of electric motors by Varying the field strengthand the electromotive force applied to the armature-terminals in amannerhereinafter described and claimed; second,to provide means wherebyall external resistance in series with the armature can be dispensedwith without jeopardiziug the smoothness of the regulation; third, to sovary the strength and character of the field-magnet of the motor at thedifferent notches on a speed-regulating controller, in combination withvariations in the voltage supplied to the armature, that the motor willautomatically become a generator, charging the batteries, (a) when thecontrolleris moved from anotch of high speed to one of lower speed, thuschecking the speed of the vehicle, and (b) when the vehicle is runningdownhill; fourth, to so increase the efficiency of the motor when actingas a generator that it always may be used as a recharging-generator inthe station by uncoupling the driving-gear of the vehicle and connectingthe motor-shaf t to any suitable source of power; fifth, to providemeans for varying the voltage at the armature-terminals and the strengthand character of the fieldmagnet in a manner that will cause therecharging feature to become effective down to such a slow speed of thevehicle that the ordinary power-wasting band-brake at the end of thearmature-shaft can be entirely dispensed with and the speed of thevehicle may be wholly governed by the controller.

Briefly expressed, the invention consists of the combination of anelectric motor, a storage battery (or the equivalent thereof) and vaspeed-regulating controller for connecting reference is made to theaccompanying draw* ings, in which- Figure l illustrates the stationaryand the developed movable contacts in a controller of the cylinder type.This ligure shows also the circuit connections between the station* arycontacts of the controller, the batteries, and the motor. Fig. 2 is adiagrammatic view of various combinations of the motor and thebattery-circuits when the movable contacts on the controller-cylinderare rotated over the stationary right-hand contacts shown in Fig. l.

Referring again to Fig. l, c c' c2, tbc., to c13 represent thestationary contacts for the main switch or speed-regulating controller,and T, T', T2, and Ts represent the movable contacts upon thecontroiler-cylinder, said contacts being shown in plan development. c,c, ci, and c17 represent the stationary contacts for a reversing-switch,the movablel contacts of said switch being represented by T4, T5, TG,and T7. B, B', B2, and B3 are groups of storage-battery cells of acapacity and voltage best suited for the motor and the vehicle. Arepresents the armature of the said motor, and F and F represent thefield-windings of the same. R is a low resistance used as a shunt forthe field-winding F at certain positions of the controller, and r and-12 are resistances arranged to be connected in series with thefield-winding F.

It will be noticed upon inspection of Fig. l that the field-winding F isconnected across the group of storage-battery cells marked B3 when thespeed-controlling switch is closed and that the other field-winding Fwhen in IOC) contacts c7 and o9 to become connected.

positive terminal of the battery through the armature and field-windingF' ofthe motor back to the negative terminal of the battery.

The numbers l, 2, 3, to 9, inclusive, above= the lines shown in dot anddash on Fig. l

indicate the various running positions or notches on thecontroller-cylinder. The circuit connections at these positions betweenthe battery groups, the armature, and the field-magnet coils are fullyillustrated in Fig. 2 by diagrams p3 pf p5, p8 p9 p10, 19121913 and vp14. There are, however, other important circuit combinations betweenthe above-mentioned positions which will,be fully pointed out in thedetailed description of the mode of f the armature-circuit by reason ofthe conoperation.

Assuming now that the reversing-switch,v

shown on the left-hand side of Fig. l is closed, causing contact 014 tobe connected with contact 015 and contact 016 with contact 017, the modeof operation may be described as follows: The mainspeed-controllingswitch,with its movable contacts T, T', T2, and T3, issupposed to be moved or rotated (from right to left) into contact withthe stationary contacts c, c', c2, to als, inclusive. By reason of thecontact T8 extending farther to the left than. vany other it followsthat contact 010 will be,

connected to contacts e, 012, and G13 before any other connection ismade. This causes the field-winding F to become separately and fullyexcited bya current from the lower group `of battery-cells B3, asillustrated by diagram p' in Fig. 2 at the extreme left of the draw-fings. A further movement of the switch causes contacts c, c', c4, and c5to become connected together, likewise contacts c2, c3. c, 'and cT-thatis to say, the four battery groups have become connected in parallel andcurrent is now flowing from the -iside of the battery groups through thearmature A in the direction of the dotted arrow, through thefield-winding F', and back to the negative side of vthe battery groups.(See Fig. l.) This is, in fact, the starting position, thecircuitconnections being fully shown by diagram p2 in Fig. 2. It will beunderstood that theV .current required for starting has been forced toflow through the field-winding F', thus producing in connection with theother field-winding the most powerful field strength. The next movementof the switch causes the stationary The field-winding F' is therebyshort cirouited, and the field strength is now solely dependent upon thecurrent iiowing through the other Winding F and is independent of thecur` rent flowing through the armature. This is These field-windings areboth arranged 2 in Fig. l) the circuit connections are retained as theywere in the first position, with the exception that the resistance r2has been connected in series with the field-winding F, thus reducing thefield strength and causing thearxnature andthe vehicle to run at anincreased speed.' The diagram p4 in Fig. 2 illustrates fully all thecircuits. Position No. 3 on the controller is similar to No. 2, with theexception that the field strength has been further reduced by means ofan additional resistance r', connected in series with the fieldwindingF.Y Said resistances r' and r2 are s0 proportioned that the speed of thearmature has increased about sixty per cent. to seventy per cent. sincethe first position of the controller. The diagram p5 in Fig. 2illustrates the connections as this third running position. A furthermovement of the switch causes the field-winding F' to be momentarily outinto tacts c7 and C9 being disconnected ahead of the other stationarycontacts. This is a transition step or position, which is illustrated bythe diagram p6 in Fig. 2. As the speed-regulating switch is moved on thearmature and the battery circuits become completely severed at the nextmoment, the only circuit which is still closed being the one through thefield-Winding F and the resistances r'and r2. Before the armature andbattery circuits are again restablishedv the resistances r' and r2 arecut out, so that the field-winding F will again become fully excited. Itwill be seen from Fig. l that when the armature and battery circuits areagain closed the battery groups B and B' are still connected inparallel, but that theyare connected in series with the other two groupsB2 and B8, which also remain in parallel with each other, as before. Itwill also be seen that at the moment 'the circuits are closed thefield-winding F' is connected in series with the armature. This is forthe purpose of causing the field strength to become considerablyincreased in case the speed of the armature should be such that anygreat amount of current would fiow through its windings. The diagram p7in Fig. 2 will give a clear idea of the circuit connections during thistransition step. As the switch is movedlonto the fourth positioncontacts c7 and a8 become connected, which causes the low resistance Rto become connected in parallel with the field-winding F'. Thisresistance is so proportioned that it will shunt about seventy-five toeighty per cent. of the current, which otherwise would flow through thefield-winding F'. If'now the maximum amount of ampere-turns from thefield-windings F' (at normal torque of the motor) is about equal to theampere-turns from the field-winding F at the lowest excitation when bothof the resistances r' and r2 are in series with the same, it followsthat the eect of the field-winding F' upon the field strength will bevery slight at this fourth position of 'the controller.- (See diagram p8in Fig. 2.) In

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other words, the field strength, and consequently the speed, is stillpractically independent of the armature-current, but as the switch ismoved on and positions 5 and G are successively reached and the fieldstrength is reduced by reason of the resistances r2 and r again beingconnected in series with the field-winding F the field-winding F' willcommence to in luence the general field strength. It will thus beunderstood that at position No. 6 of the controller (see diagram p10 inFig. 2) the field strength of the motor, and consequently the speed ofthe vehicle,becomes somewhat responsive to variations in thearmature-current. In other words, if the vehicle should happen to gouphill the eld strength would be somewhat increased and the speedcorrespondingly decreased. A further movement of the switch causes thefieldwinding F to be completely cut into the armature-circuit duringanother transition step, the utility of which will be explained later.(See diagram pu of Fig. 2.) As the switch is moved on the armature andthe battery connections are again severed. The next instant theresistances r2 and r' are again cut out, causing the field-winding F toyield its maximum amount ot' ampereturns, and when position No. 7 isreached the battery groups B, B', B2, and B3 are all connected in serieswith each other and with the armature and the eld-coil F', as clearlyshown by diagram p12 of Fig. 2. that although the excitation of thefield is quite great from the field-winding F alone the other winding F(not being shunted) will increase the field strength if it should happenthat a strong current would be fiowing through the armature-circuit inthe direction of the dotted arrow. (See Fig. l.) The infiuence of thesaid field-winding F' will of course increase as the ampere-turns of theother field-winding F are again successively reduced at positions Nos. Sand 9 of the controller. (See diagrams p13 and p14 of Fig. 2.) Itfollows, then, that if the vehicle were ascending a grade the eldstrength would be materially increased and the speed reduced, which inturn would save the battery from too great a rate of discharge, it beingof great importance that the rate of discharge should not be too greatwhen the cells are all in series.

It will now be understood from the above description that the speed ofthe vehicle at the three first notches or positions of the controllerwill be practically independent of the direction or the strength of thearmaturecurrent. The batteries will of course have ample ampere capacitywhen connected in parallel, and no harm to the batteries can result fromthe fact that the character of the field strength is of such a naturethat the motor will fight or take current through its armature inproportion to the required torque. At the three next positions of thecontroller there is still enough ampere capacity in the various groupsof batteries to permit the field It should now be pointed out strengthto be fairly independent of the armature-current; but at the three lastposi tions of the controller, when the cells are in series and thevoltage is four times as great as in the three first positions, greatcare must be taken that the permissible rate of discharge may not beexceeded. For this reason the character of' the field strength has beenchanged in a manner that will cause the motor to reduce its speed atheavy loads-'t'. c., it will automatically increase its field strengthand will th us limit the current flowing through the armature. y

It will of course be understood from the foregoing description that themotor will have a very wide range of speed, from the slowest speed atlow voltage and strong field to the highest speed at four times thevoltage with a weak field. The battery-cells in B3, which are calledupon to furnish current for the field-winding F, may preferably be ofsomewhat greater' capacity than the other cells.

supposing nowl that the controller is at the last notch and the vehicleis running ata high rate of speed, it will be evident that as thecontroller or switch is moved toward the off position the momentum ofthevehicle will soon cause the motor to work as a dynamo, recharging thebatteries and checking the speed ofthe vehicle. The checking will bequite gentle at first, owing to the fact that as the current reverses inthe armature it will also reverse its direction in the field-winding F,and thus reduce the field strength; but even at the seventh position ofthe switch the checking effort and the recharging capacity will beconsiderable on account of the strong field from the winding F. As thecontroller is moved on toward the off position the motor becomes moreand more efficient as a dynamo, checking the speed of the vehicle andrecharging the batteries until at the first position of the controllerthe speed of the vehicle is reduced to a minimum and the rechargingaction ceases. As the speed is extremely low at the first notch, aslight pressure on the ordinary foot-brake will bring the vehicle torest when the switch is thrown to the off position.

The general operation of the motor as arecharging-dynamo now beingunderstood, the utility of the transition steps previously referred toand illustrated by diagrams pu, 19", p6, and p2 should be pointed out.Assuming, then, that the speed ot the vehicle is being rapidly reducedby the controller heilig thrown from a position of fairly high speed toone of considerably lower speed-for instance, from position No. 5 to No.3 or No. 2- it becomes evident that unless the field strength can bemade to respond instantaneously there is danger of shock to theapparatus as the controller goes over from position No. 4 to No. 3because ot` the sudden change in voltage. In other words, itbeinstantaneously.

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, is'reached the held-winding F is cut in, re-

ducing the field strength on account of the reversed current in saidWinding. The arnpere-turns ofthe 'field-winding F are next reduced, andin case the lield strength or the iield uX should not simultaneouslyrespond to the reduction in ampere-turns the demagnetizing eiect of thecurrent in the field-coil F as the circuits are again closed willeffectively prevent a too sudden recharging action and a consequentshock to the apparatus.

The transition steps may thus be said to soften or cushion the effect ofthe motor upon the vehicle at the series-parallel changes of thebattery-circuits. Should the vehicle be running downhill, the motor willof course work eiliciently as a recharging-generator at any position ofthe controller (dependent upon the desired speed) from the first notchto and inclusive of the seventh notch.

Recharging at the station can conveniently be done by uncoupling thedriving-gear for the vehicle and running the motor as a dynamo from anysuitable source of motive power. The controller will then govern therate of charging precisely as if the vehicle were running down a longhill, and the usual instruments at the foot of the dashboard willindicate how and when the batteries are charged. The finishing chargeshould be made at a speed corresponding to any of the first threenotches when the batteries are in parallel.

Having thus described my invention, what I claim, and desire to secureby Letters Patent of the United States, is-

1. In an electrically-propelled vehicle the combination with an electricmotor and two or more groups of batteries arranged to be connected inparallel or in series to the motor by a speed-regulating controller, ofmeans for causing the field strength ot' the motor t-o becomepractically independent of the armature current when the batteries areconnected in parallel, but responsive to variations in thearmature-current when the 'batteries are connected in series,substantially as described.

2. The combination with an electric mot-or of two or more groups ofelectric batteries, a circuit-changing switch or controller forconnecting the various groups of batteries to the motor in parallel orin series; means, such as a separately-excited field, for causing thespeed of the motor to become practically independent of thearmature-current when the battery groups are in parallel, with othermeans for causing the speed to become responsive to fiuctuations in thearmature-current when the battery groups are in series and when theseries-parallel changes of the battery-circuits are made.

3. An electricl motor ot' the regenerative type the speed of which ischieiy governed by changes of the electromotive force applied to thecommutator or armature terminals; in combination with means, such asseries coils momentarily cut into the main circuit, for automaticallyadjusting the field strength at the time the abovementioned changes ofelectromotive force are effected.

4. The combination of an electric-circuit controller, an electric motoror/motors the speed of which is chiefly governed by changes of theelectromotive force applied to the armature-windings, means forautomatically adjusting the field strength, t'. e. strengthening orweakening the same, at the time the said changes of electromotive forceare effected, with additional means for keeping the field strengthpractically independent of the ar-

